PMC

(A) Synchronous sliding between the doublet Nos. 7 and 8 generates a large fiber loop of the doublet microtubule Nos. 4–7 at the midpiece and forms an asymmetrical planar bend. The sliding displacement of the synchronous sliding is dependent on the Ca²⁺ concentration. Higher Ca²⁺ concentrations produce larger sliding displacements [,,]. (B) Metachronal sliding between the doublet Nos. 3 and 4 retracts the extruded fiber of the doublets Nos. 4–7 into the flagellum, followed by metachronal sliding between the doublets Nos. 2 and 3 in two loci on the flagellum. The sliding at the base of the midpiece generates a small fiber loop for the doublets Nos. 9–2 and the sliding at the distal region of the flagellum begins to induce metachronal sliding between the doublets Nos. 1 and 2. (C) Metachronal sliding propagating towards the tip and simultaneously transferring in the sequence of doublets Nos. 1, 9, 8, and 7 leads to the generation of a left-handed helical bend at a distal region of the flagellum at low Ca²⁺ concentrations [,,]. The numbers in the circles indicate the number of the doublet microtubules according to Afzelius []. The numbers indicate the sliding of corresponding doublet microtubules. The synchronous sliding superimposed on the metachronal sliding converts a helical bend into a half-funnel shape.

Typical sliding positions of a player at base arrival: (A) arriving in a head-first slide; (B) arriving in a feet-first slide.

(A) Sliding of pucks (with polymer sheet bases) on cellulose (on inclined plane) causes tribocharging of the surfaces and leads to an increase in friction. (B) Sliding time of the puck and charge acquired on the base both increase with repeated sliding runs. When the sliding surfaces are discharged by a Zerostat corona discharge gun, the sliding time resets back to the value in the first sliding (green arrow) [puck = wood (2 cm diameter); polymer sheet = PET (2 cm diameter, 0.20 mm thick); θ = 20°] (C) θ, in which the sliding can be initiated on the inclined plane at the repeated cycles, increasing with tribocharging at repeated cycles; again, reset is possible by corona discharging [puck = wood (2 cm diameter); polymer sheet = PTFE (1.5 cm diameter, 3.0 mm thick); relative humidity = 22%; see movie S2 and the Supplementary Materials for further experimental details].

Representative time courses (A-C) and statistical distributions (D-F) of the sliding coordinate (the deviation of the base pair initially at the dyad from its starting configuration) for each considered sequence: polyCG (A,D), polyCG-601 (B,E) and 601 (C,F). The time courses were moving averaged over 10 time points.